1. Field of the Invention
The invention relates to a spring-loaded compression or tension pin according to the introductory part of Claim 1. Such spring-loaded compression and tension pins are known in their embodiment as machine elements where there is a need to locate or hold elements with a spring-loaded compression pin which engages in a suitably adapted mating surface.
2. Description of the Related Art
By releasing the spring-loaded compression pin from a surface to which it has been assigned, the connection between the compression pin and that surface can be unmade. Such a component has a variety of uses as a machine part, and essentially comprises an outer bush which has an external screw thread and an internal bore.
A spring-loaded plunger is inserted in this bore, with one end resting on the spring. The spring rests on a bearing surface inside the bush. This bearing surface is fixed with respect to the housing.
Thus the plunger is axially displaceable under spring loading inside the internal bore of the externally threaded bush.
By exerting a pulling force on the plunger, the force of the spring can be overcome and the plunger displaced inside the bush, thus unlocking the plunger from the opposing machine surface.
Such spring-loaded elements have proved effective. However, they have the drawback that the mounting of the plunger in the receiving bore in the threaded bush does not restrain the plunger in the torsional direction. This has hitherto been unnecessary, as the front end of such plungers is usually given a round (or similarly rotationally symmetrical) profile, so that torsional restraint is not important.
But there are various applications in which torsional restraint is important, for example where the plunger is to be positioned on a projecting edge. The plunger then has to be given suitably profiled faces which will clasp the edges. This presupposes that the plunger is torsionally restrained, otherwise there can be no certainty that the profiled edge on the plunger will be aligned with the opposing edge, which is itself fixed with respect to the machine.
Therefore the basic problem of the invention is to develop a spring-loaded compression or tension pin of the kind stated at the outset so that the plunger is held in the threaded bush in a torsionally restrained manner.